The extended Attribute Exchange now enables "Relying Party" sites to request first and last name, country and preferred language, in addition to email address (which was already available), when a user authenticates.

The popup user interface provides an alternate means for accessing the Google approval window. As Yariv Adan explains on the Google Code Blog:

The new popup style UI, which implements the OpenID User Interface Extension Specification, is designed to streamline the federated login experience for users. Specifically, it's designed to ensure that the context of the Relying Party website is always available and visible, even in the extreme case where a confused user closes the Google approval window. JanRain, a provider of OpenID solutions, is an early adopter of the new API, and already offers it as part of their RPX product. As demonstrated by UserVoice using JanRain's RPX, the initial step on the sign-in page of the Relying Party website is identical to that of the "full page" version, and does not require any changes in the Relying Party UI.

These new changes provide a means for improving the user experience and streamlining the authentication process using a Google account. We're looking forward to seeing how the API will be expanded and enhanced in the near future, and curious to see how readily it will be adopted by sites looking to leverage OpenID via Google.